Motorized damper operator and control

ABSTRACT

An electric motor driven operator and control for dampers of the gravity return type, such as used in chimney flues for fireplaces. The operator comprises an electric motor-gear speed reduction unit for driving a crank arm which engages with a pivoted member in an elongated slot in the latter. In each revolution of the output shaft of the driving unit the pivoted member opens the damper in the first half revolution, and then allows it to close in the remaining half revolution. The control comprises a two position selector switch, and limit switch operable in accordance with the motor shaft position to cause the motor to stop when the damper is in full open position, or when in completely closed position. Indicating lights are provided to indicate when the damper is in open position, and when the temperature in the region of the damper operator exceeds a predetermined high limit.

United States Patent [1 1 Schreibeis 51 Nov. 20, 1973 MOTORIZED DAMPER OPERATOR AND CONTROL [75] Inventor: John J. Schreibeis, Smithfield, NC.

[73] Assignee: Cutler-Hammer, Inc., Milwaukee,

Wis.

{22] Filed: Dec. 9, 1971 21 Appl. No.: 206,396

[52] US. Cl. 126/285 B, 431/14 [51] Int. Cl. F231 11/00 [58] Field of Search 126/285 B, 288, 295; 431/13, 14

[56] References Cited UNITED STATES PATENTS 3,010,451 11/1961 l-lodgins 126/285 B 3,580,238 5/1971 Diehl 126/295 2,082,298 6/1937 Moran 126/288 2,224,705 12/1940 Stringer 126/285 B 2,357,642 9/1944 Firehammer.. 126/285 B 3,096,754 7/1963 Howrey 126/ 120 Primary ExaminerMeyer Perlin Assistant Examiner-Ronald C. Capossela Attorney-Hugh R. Rather et al.

[57] ABSTRACT An electric motor driven operator and control for dampers of the gravity return type, such as used in chimney flues for fireplaces. The operator comprises an electric motor-gear speed reduction unit for driving a crank arm which engages with a pivoted member in an elongated slot in the latter. In each revolution of the output shaft of the driving unit the pivoted member opens the damper in the first half revolution, and then allows it to close in the remaining half revolution. The control comprises a two position selector switch, and limit switch operable in accordance with the motor shaft position to cause the motor to stop when the damper is in full open position, or when in completely closed position. Indicating lights are provided to indicate when the damper is in open position, and when the temperature in the region of the damper operator exceeds a predetermined high limit.

6 Claims, 2 Drawing Figures 1 MOTORIZED DA PER OPERATOR AND CONTROL BACKGROUND OF THE INVENTION In certain localities, fireplaces for the burning of logs and Other solid fluels are more or less regularly used either as a primary, or atheistically pleasing supplementary'means of heat. Such fireplaces normally have a gravity return type damper installed in a restricted flue area leading to'the chimney" to shut Off'unwantedupflow of air through the chimney when thefireplace" is not in use. Normally, some'form of manually operable means is provided to'set' .the damper in desired open and closed positions. Operation of such mechanisms are apt to cause soiled handsand clothes and usually they do riot provide ready indication of the damper position.

oEJEcT OF THE INVENTION It is an object of the present invention to provide an improved electric motor driven damper operating mechanism for dampers of the aforementioned type, for control at a desiredp'oint outside of the fireplace and chimney areas.

Another object of the invention is to provide a damper operator andcontroller of the aforementioned type which is Characterized by affording stopping of the damper in fully open and fully closed positions'as' desired. I

A" further object of the invention is to provide a damper control of the aforementioned type providing remote indication of damper opening and indication of excessive temperature in the region where the damper operator is mounted.

Still another object of the invention is to provide a damper operator and control of the aforementioned type which does not interfere with or prohibit conventional manual opening, closing, and positioning of the damper when desired. Other objects and advantages of the invention will hereinafter appear.

BRIEF DESCRIPTION OET'I'IE DRAWINGS FIG. 1 is a diagrammatic showing of a motor damper operator and control therefor constructed in accordance with the invention; and

FIG; 2 is a fragmentary view in vertical cross-section I of a fireplace chimney flue and the" preferred form of the damper operator mounted therein.

DESCRIPTION OETIIE REFERRED EMBODIMENT Referring to FIG. 1, it shows a motor damper operator 4 comprising an electric Inotor-gear speed reduction unit 6 having an electric driving motor 6a and an output shaft 6bonwhich is mounted a crank arm 8. Adjacent its free end, crank arm" 8is filled with a freely rotatable'roller'tla which engages withinan elongated 'slot 10a of a member 10 'vvhichis pivotally rotatable at 10b. An end 100 is engagable with adarnper 12 which is pivotally mounted at- 30a. It may be assumed that inthe position of crank arm"8,-niember 10 and damper 12 depicted that thelatter is in its full open position.

h Ald amper control unit 14 is provided, and comprises a two-position selector switch 16, indicating lights 18 and 20 and a fuse 22. A'.C. power lines L1 and L2 are adapted to be connected to the power input terminals 24a and 241; on unit 14. Terminal 24a is connected in series with fuse 22 to input terminal 16a of switch 16 which has stationary output terminals 16b and and a movable contactor 16d. The point common between fuse 22 and terminal 16a of switch 16 is connected in series with indicating light 20, which is preferably red in color, and in series with a normally open bi-metallic thermally responsive switch 26 to power terminal T1 of motor 6a. 1 v

Output terminal 16b of switch 16 is connected to input terminal 28a of a two-position limit switch 28 which has a second input terminal 2812, an output terminal 28c and a movable contactor 28d. Output termi- Ininal28b of limit switch 28 and output terminal 280 of the latter is connected to power input terminal T2 of motor 6a. Indicator light 18, which is preferably green in color, is connected between terminal 16b of switch 16 and input terminal 24b.

As will hereinafter be more fully explained, limit switch 28 is operated by a cam driven by the output shaft 6b of unit 6, and changes the operating position of contactor 28d between input contacts 28a and 28b each one-half, or of a full revolution of shaft 6. The'positions of selector switch 16, limit switch 28 and damper 12 depicted in FIG. 1 are those affording full open positioning of damper 12. Indicating lamp 18 will be illuminated from line L1, through switch 16 to line L2 to provide an indication that the damper is open.

If it is desired to close damper l2, selector switch 16 is operated to close contactor 16d to contact 16c for completion of circuit from line-L1 through switch 28 into terminal T1 and out from terminal T2 to line Ll. Motor 6a will then be energized tocause rotation of shaft6b clockwise and thereby cause member 10 to correspondingly pivot clockwise. Damper 1 2, which may be assumed to be gravity biased to move to its closed position, will then likewise pivot in that clockjwise direction. When crank arm 8 reaches a' position of 180 opposite that depicted in FIG. 1, limit switch 28 operates to move its contactor 28d out of engagement with terminal 28b and into engagement with contact 28a.This interrups the power connection to terminal T2 and unit 6 stops the rotation of its output shaft 6a. It may be assumed that damper 12 has then reached its fully closed position, and indicating la mp 18 will of course be deenergized by the operation of switch contactor to open from contact 16b in switch 16.

As will be apparent if the ambient temperature of the air in the vicinity of operator unit 4 reaches a predetermined high temperature, thermally responsive switch 26 will close to provide an energizing circuit for indicator lamp 20 across lines L1 and L2 to provide a warning indication of possibly destructive temperatures.

FIG. 2 shows a preferred actual embodiment for the operator unit 4 and damper 12 mounted in a chimney flue of a fireplace. More particularly, damper 12 is pivotally mounted on the edge of a plate 30 at 30a secured in the side wall 32a of a chimney flue and is adapted to close against the inwardly projecting leg 34a of an angle bracket 34. The other leg 34b of bracket 34 abuts against an inwardly and upwardly sloping position 320 formed on the opposite vertical wall 32b of the chimney flue. The leg 36a of another angle bracket 36 overlies the leg 34b and these abutting legs of the brackets are secured in place by lag bolts 38 penetrating aligned openings in such legs and secured in the portion 32c of the chimney flue. The other leg 36b of bracket 36 supports motor-gear speed reduction unit 6, limit switch 28 and thermally responsive switch 26. Bracket 36 ad-. jacent its free end provides support for a pivot pin 40 on which member is pivotally mounted.

Preferably member 10 is of the L-shape form depicted in FIG. 2 and has the aforementioned slot 10a formed in the leg 10d. The other leg 10c adjacent the end 100 is provided with a stub shaft on which is mounted a freely rotatable roller 10f that engages the damper 12. A cam 42 is non-rotatably secured on the output shaft 6a of unit 6 and has two 180 peripheral cam surfaces. One cam surface 42a is of one continuous radius and the other cam surface 42b is of a slightly greater continuous radius. As depicted in FIG. 2, cam surface 42b has just depressed the actuator 28f of limit switch 28 to provide the operating condition shown in FIG. 1 for switch 28. It will be seen that in the next half revolution of shaft 6a, switch 28 will remain in that same position until the actuator 28f of switch 28 engages with cam surface 28a. When this occurs, the actuator 28f releases and switch 28 will operate to the condition opposite to that shown in FIG. 1 in which contactor 28d engages with contact 280.

The operator unit 4 is preferably surrounded by a generally U-shaped channel or duct 44 which has its parallel leg portions 44a secured to the portion 32c of the wall 32b of the chimney flue. Channel 44 is also provided with a bight leg portion 44b which terminates at a point below and inside the outerwall of chimney wall 32b. When damper 12 is open as shown in FIG. 2 and a fire is burning in the fireplace below the damper operatorunit, chimney action will draw in relatively cool air up through the duct and around the operator unit to mix with hot air and gases generated by the burning fuel in the fireplace. This will normally prevent high heat damage of motor-gear reduction unit 6 and limit switch 28. Of course, if the temperature of the gases surrounding the operator unit 4 should rise too high, temperature thermal switch 26 would close to effect energization of red indicator lamp 20.

Units 4 and 14 are preferably both electrically grounded as depicted in FIG. 1 for protection of the users. Unit 14 preferably is mounted in a sheet metal enclosure located at a point somewhat remote from unit 12, such as in the outer side wall of the fireplace or on the fireplace mantle. The operator unit 6, limit switch 28, and electrical wiring between unit 6, switch 28 and control unit 14 should preferably be made of high heat resistant materials available on the commercial market.

It will be apparent that the damper operator and control units of the present invention will permit noninterferring manual operation of the damper as well.

I claim:

I. The combination with a pivoted, gravity return type damper in a chimney flue and means operable to open said damper and when said damper is open to allow it to close under gravity bias comprising:

a. a'member mounted for pivoted movement and engagable with said damper, said member having an elongated slot formed therein,

an electric motor-gear speed reducing unit having an output shaft, I

c. a crank arm secured to said output shaft and having a portion engaging said member within said slot, and I control means comprising a selector switch operable to one position when said damper is in closed position to energize said motor and thereby rotate said crank arm and pivot said member in a given direction to open said damper and further comprising switch means operable when said. damper reaches full open position to deenergize said motor, said selector switch being operable to another position when said damper is fully open to energize said motor to rotate said crank arm further in the same direction and pivot said member in an opposite direction away from said damper to allow the latter to close under gravity bias, and said switch means also operating when said damper reaches closed position to deenergize said motor.

2. The combination according to claim 1 wherein said control means further includes an indicating lamp which is energized whenever said selector switch is in said one position.

3. The combination according to claim 2, wherein said control means also includes a second indicating lamp and a thermally responsive switch in circuit therewith for mounting in the chimney flue in proximity to the damper driving unit, said thermally responsive switch closing to energize said second indicating lamp whenever it is subjected to temperatures above a predetermined high limit.

4. The combination according to claim 1 wherein said switch means comprises a limit switch in circuit with said selector switch, and a cam driven by said output shaft, said cam having a circumferential cam surface such that said limit switch assumes one operating condition during one-half revolution of the output shaft, and another operating condition for the remaining portion of each output shaft revolution.

5. The combination according to claim 1 wherein said member is L-s'haped and the slot is in the leg which is pivoted and wherein the other leg of said member has a roller rotatably mounted adjacent its free end which engages with said damper.

6. The combination according to claim 4 wherein said motor gear speed reducing unit, said crank arm, said member mounted for pivotal movement, and said switch means when mounted in a chimney flue are provided with a partially enclosing duct having an entrance extending into the fireplace opening to convey relatively cool air up and around such elements whenever said damper is open toafiord chimney drawing action. l 8 =0 

1. The combination with a pivoted, gravity return type damper in a chimney flue and means operable to open said damper and when said damper is open to allow it to close under gravity bias comprising: a. a member mounted for pivoted movement and engagable with said damper, said member having an elongated slot formed therein, b. an electric motor-gear speed reducing unit having an output shaft, c. a crank arm secured to said output shaft and having a portion engaging said member within said slot, and d. control means comprising a selector switch operable to one position when said damper is in closed position to energize said motor and thereby rotate said crank arm and pivot said member in a given direction to open said damper And further comprising switch means operable when said damper reaches full open position to deenergize said motor, said selector switch being operable to another position when said damper is fully open to energize said motor to rotate said crank arm further in the same direction and pivot said member in an opposite direction away from said damper to allow the latter to close under gravity bias, and said switch means also operating when said damper reaches closed position to deenergize said motor.
 2. The combination according to claim 1 wherein said control means further includes an indicating lamp which is energized whenever said selector switch is in said one position.
 3. The combination according to claim 2, wherein said control means also includes a second indicating lamp and a thermally responsive switch in circuit therewith for mounting in the chimney flue in proximity to the damper driving unit, said thermally responsive switch closing to energize said second indicating lamp whenever it is subjected to temperatures above a predetermined high limit.
 4. The combination according to claim 1 wherein said switch means comprises a limit switch in circuit with said selector switch, and a cam driven by said output shaft, said cam having a circumferential cam surface such that said limit switch assumes one operating condition during one-half revolution of the output shaft, and another operating condition for the remaining portion of each output shaft revolution.
 5. The combination according to claim 1 wherein said member is L-shaped and the slot is in the leg which is pivoted and wherein the other leg of said member has a roller rotatably mounted adjacent its free end which engages with said damper.
 6. The combination according to claim 4 wherein said motor gear speed reducing unit, said crank arm, said member mounted for pivotal movement, and said switch means when mounted in a chimney flue are provided with a partially enclosing duct having an entrance extending into the fireplace opening to convey relatively cool air up and around such elements whenever said damper is open to afford chimney drawing action. 